Dye developer processes and products using naphth{8 1,2-d{9 imidazole

ABSTRACT

This application is concerned with the use of naphth(1,2d)imidazole in dye developer diffusion transfer processes.

United States Patent 11 1 [111 3,909,264

Bloom Sept. 30, 1975 [54] DYE DEVELOPER PROCESSES AND [56] References Cited PRODUCTS USING UNITEDSTATES PATENTS NAPHTHILZ-DIIMIDAZOLE 3,260,597 7/1966 Weyerts et a1, 96/3 [75] Inventor: Stanley M. Bloom, Waban, Mass. 3265'498 8/1966 Rogers et a! 3,353,956 ll/l967 Rogers et al [73] Assignee: Polaroid Corporation, Cambridge, 3,377,166 4/1968 Weyerts et al Mass, 3,785,814 1/1974 Land et al 96/3 [22] Filed: 1973 Prinzar Examiner-Norman G. Torchin [21] Appl. No.: 428,382 Assistant E.\'aminer Richard L. Schilling Attorney, Agent, or Firm-Stanley H. Mervis [52] U.S. Cl 96/3; 96/663; 96/76 C;

57 ABSTRACT 96/77 1 [51] Int Clg G03C7/00 G03C1/48 G03C5/3O, This application is concerned with the use of 003C 6 naphth[l,2-d]imidazole in dye developer diffusion 58 Field Of Search 96/3, 77, 76 c, 66.3 transfer Processes 11 Claims, 2 Drawing Figures REFLECTION oeusm 0 T '7' P in 5 a0 2.8 2.6 2.4 2.2 20 L8 L6 L4 L2 1.0 .e .s 6 .e

LOG E REFLECTION DENSITY REFLECTION DENSITY wwwawa- U8. Patent Sept. 30,1975

0 2.8 216 214 2.2 20 L8 L6 |.4 I 1.2 lb .6 i A 0 30 218 2'6 214 2.2 2.0 l8 L6 |'4 l2 I0 8 e 4 2 B DYE DEVELOPER PROCESSES AND PRODUCTS USING NAPHTH[ l ,2-D]IMIDAZOLE This invention is concerned with color photography and, more particularly, with photographic processes which provide dye developer diffusion transfer color images.

U.S. Pat. No. 2,983,606 issued May 9, 1961 to Howard G. Rogers, and numerous other patents disclose photographic processes employing dye developers and, in particular, the formation of diffusion transfer color images by the use of dye developers.

The present invention is concerned with the use of naphth[l,2-d]imidazole in such dye developer photographic processes.

The primary object of this invention is to provide novel photographic processes wherein an exposed silver halide emulsion is developed in the presenceof a dye developer and naphth[ l,2-d]imidazole.

A further object of this invention is to provide novel multicolor dye developer diffusion transfer processes wherein the blue H and D curve may be preferentially shifted relative to the red and green H and D curves, to obtain more desirable flesh tones, by performing said process in the presence of naphth[l,2-d]imidazole.

Other objects of this invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the product possessing the features, properties and the relation of components and the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others which are exemplifled in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. 1 reproduces the characteristic curves of the red, green and blue densities of a simulated flesh tone .color column of a multicolor transfer print obtained in :accordance with this invention; and

FIG. 2 reproduces the characteristic curves of the red, green and blue densities of a simulated flesh tone color column of a multicolor transfer print obtained in a control experiment and reproduced for comparison purposes.

This invention is particularly directed to photographic processes wherein the desired color transfer image is a multicolor image obtained by processing an exposed multicolor photosensitive silver halide element with a processing composition distributed between two sheet-like elements, one of said elements including an image-receiving layer. The processing composition is so applied and confined within and between the two sheet-like elements as not to contact or wet outer surfaces of the superposed elements, thus providing a film unit or film packet whose external surfaces are dry. The processing composition, which may be viscous or nonviscous, preferably is distributed in viscous form from a single-use rupturable container; such pressure rupturable processing containers are frequently referred to as pods.

Multicolor diffusion transfer images may be obtained using dye developers by several techniques. A particularly useful technique employs an integral multilayer photosensitive element. such as is disclosed in the aforementioned U.S. Pat. No. 2,983,606, and particularly with reference to FIG. 9 thereof, and also in U.S. Pat. No. 3,345,163 issued Oct. 3, 1967 to Edwin H. Land and Howard G. Rogers, wherein at least two selectively sensitized photosensitive strata, superposed on a common support, are processed, simultaneously and without separation, with a single (common) imagereceiving layer. A suitable arrangement of this type for obtaining multicolor images utilizing subtractive color principles comprises a support carrying a red-sensitive silver halide emulsion stratum, a greensensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be positioned in the silver halide emulsion stratum, for example in the form of particles, or it may be disposed in a stratum behind the appropriate silver halide emulsion stratum with respect to the exposing light. Each set of silver halide emulsion and associated dye developer strata may be separated from other sets by suitable interlayers, for example, by a layer or stratum of gelatin, polyvinyl alcohol, or other polymeric materials known in the art. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion to avoid improper exposure of said emulsion, by blue light, and such a yellow filter may be incorporated in the appropriately positioned interlayer. However, such a separate yellow filter may be omitted where a yellow dye developer of the appropriate spectral characteristics is present in a quantity and state capable of functioning as the requisite yellow filter. Procedures and suitable components for preparing such integral multicolor photosensitive elements are described in numerous patents and are well known in the art.

Following photoexposure, the photosensitive element is processed by application of a processing composition, for example, by immersion, coating, spraying, flowing, etc., in the dark. The exposed photosensitive element may be superposed prior to, during, or after application of the processing composition on a sheetlike element which may include an image-receiving layer. In one commercial embodiment, the processing composition is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed relationship with the image-receiving layer. The liquid processing composition permeates the layers of the photosensitive element to initiate and effect development of the latent images contained therein. The dye developers are immobilized or precipitated imagewise in developed areas as a consequence of and in proportion to the silver halide development. This immobilization is, at least in part, due to a change in the solubility characteristics of the dye developers upon oxidation and especially as regards its solubility in alakline solution. In undeveloped and partially developed areas of the silver halide emulsion layers, the respective unoxidized (unreacted) dye developers are diffusible. Development thus provides an imagewise distribution of unoxidized dye developer, diffusible in the alkaline processing composition, as a function of the point-to-point degree of exposure of a silver halide emulsion layer. At least part of each of these imagewise distributions of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer, said transfer substantially excluding oxidized dye developer. The image-receiving layer receives a depthwise diffusion, from each developed silver halide emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribu- I tion thereof to'provide a reversed or positive color image of each developed silver image. The imagereceiving layer may contain a mordant and/or other agent to immobilize the dye developer transferred thereto. If the color of a transferred dye developer is affected by changes in the pH of the image-receiving layer, this pH may be adjusted in accordance with wellknown techniques to provide a pH affording the desired color. In the preferred embodiments of said U.S. Pat. No. 2,983,606 and in certain commercial applications thereof, the desired positive multicolor image is viewed by separating the image-receiving layer from the photosensitive element at the end of a suitable imbibition period.

In a more recent commercial application of the dye developer process, the image-receiving layer is not separated from its superposed relationship with the photosensitive layers subsequent to transfer image formation. Instead, the color image in the image-receiving layer is viewed through a transparent support. The aforementio'nsq'up's. Pat. No. 2,983,606 discloses such an em bodiinent, the processing composition including a white pigment, such as titanium dioxide, in a quantity effective to'mask or high from view the developed silver halide emulsions now positioned behind the image-receiving layer when the image-receiving layer is viewed through the transparent support.

U.S. Pat. No. 3,415,644 issued Dec. 10, 1968 in the name of Edwin H. Land, discloses and claims photographic products and processes wherein a photosensitive elementand an image-receiving element are maintained in fixed, superposed relationship prior to exposure, and this relationship is maintained as a laminate after processing and transfer image formation. The multicolor transfer image is viewed through a transparent (support) sheet against a reflecting, i.e., white, background. Photoexposure is made through said transparent support and the layers carried thereon, including the image-receiving layer, and application of the processing composition provides a layer of lightreflecting material to provide a white background. The light-reflecting material (referred to in said patent as an opacifying agent) is preferably titanium dioxide but a number of other materials have been disclosed as useful. In addition to providing a masking layer so the transfer image may be viewed without interference by the images in the developed silver halide emulsions, the light-reflecting material also performs an opacifying function by reflecting ambient light passing through the image-receiving layer and its transparent support when the photoexposed film unit is removed from the camera before transfer image formation is completed, thereby acting to protect the photoexposed silver halide emulsions from post-exposure fogging by such light.

U.S. Pat. No. 3,647,437 issued Mar. 7, 1972 to Edwin H. Land is concerned with improvements in the above-mentioned processes, and discloses the provision of a light-absorbing material, sometimes referred to as an optical filter agent, to permit such processes to be performed outside of the camera in which photoexposure is effected and to be so performed under much more intense ambient light conditions. The light absorbing material or optical filter agent, preferably a dye, is so positioned in the film unit and/or constituted as not to interfere with photoexposure (by absorbing light during photoexposure) but so positioned between the photoexposed silver halide emulsions and the transparent support during processing after photoexposure as to absorb light which otherwise might fog the photoexposed emulsions. Furthermore, the light-absorbing material is so constituted and/or positioned after processing as not to interfere with viewing the desired image in its proper colors shortly after said image'has been formed. In the preferred embodiments, the optical filter agent is a dye and is initially contained in the processing composition together with a light-reflecting material, e.g., titanium dioxide. The concentration of this light-absorbing dye is selected to provide the light transmission opacity required to perform'the particular processunder the selected light conditions, and a plurality of such dyes selected to togetherprovide absorption over the visible spectrum is utilized in multicolor embodiments. I V

In a particularly useful embodiment, the lightabsorbing dye is highly colored at the pH of the processing composition, e.g., 13-14, but is substantially non-absorbing of visible light at a lower pH, e.g., less than 10-12. This pH reduction maybe effected by an acid-reacting reagent appropriately positioned in the film unit, e.g., in a layer between the transparent support and the image-receiving layer. Suitable acidreacting reagents, preferably polymeric acids, are disclosed in the aforementioned U.S. Pat. Nos. 3,415,644 and 3,647,437 to which reference may be made for more specific information. i 4

Suitable materials for use as the image-receiving layer are disclosed in the aforementioned patents. Preferred image-receiving layers comprise polyvinyl alcohol or gelatin containing a dye mordant such as poly-4- vinylpyridine, as disclosed in U.S. Pat. No. 3,148,061, issued Sept. 8, 1964.

As disclosed in the previously cited patents, the liquid processing composition referred to for effecting multicolor diffusion transfer processes comprises at least an aqueous solution of an alkaline material, for example, sodium hydroxide, potassium hydroxide, and the like, and preferably possesses a pH in excess of 12, and most preferably includes a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. Preferred film-forming materials comprise high molecular weight polymers such as polymeric, water-soluble ethers, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose, which are substantially inert in alkaline solution. Other film-forming materials or thickening agents whose ability to increase viscosity is unimpaired if left in alkaline solution for extended periods of time also may be used. The film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity appropriate for the particular method of application to be used, such viscosity being in excess of cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

Dye developers are well known in the art and are compounds which contain both a silver halide developing function and the chromophoric system of a dye. By

a silver halide developing'function is meant a grouping adapted to develop exposed silver halide. The dye developer as incorporated in the photosensitive element may have a latent silver halide developing function, i.e., the dye developer inay lcont ain a moiety which is a precursor of the silver halide developing function or moiety, the active functional group being formed in situ following application of the processing composition, e.g., by alkaline hydrolysis of an esterified hydroquinonyl group. A preferred silver halide developing function is a hydroquinonyl group. Other particularly useful developing functions include orthodihydroxyphenyl and orthoand para-amino substituted hydroxyphenyl groups. In general, the developing function includes a benzenoid silver halide developing function, that is, an aromatic silver halide developing,

groupwhichforms quinonoid or quinone substances when oxidized. The dye developers usually are selected for their ability to provide colors useful in carrying out subtractive color photography, e.g., cyan, magenta and yellow. Other colors, of course, may be provided to meet the needs of a particular system.

For convenience, the disclosures of the abovementioned U.S. Pat. Nos. 2,983,606, 3,415,644 and 3,647,437 are hereby incorporated herein, as is the disclosure of the copending application of Edwin H. Land,

Stanley M. Bloom .'and Howard G. Rogers, Ser. No. 246,669 filed Apr. 24, l972(now US. Pat. No. 3,801,318, issued Apr. 2, 1974).

In such'multicolor applications of diffusiontransfer color processes, variations in manufacturing conditions may result in undesired variations in the sensitometricshift in color balance, e.g., toward the blue. The present invention is concerned with reducing or avoiding such effects by performing the process in the presence of a reagent effective to improve the sensitometric response of a multicolor photosensitive element which would exhibit such undesired effects if processed in the absence of s aid reagent.

In accordance with this invention, it has been found that multicolor dye developer transfer images having more desirable sensitometric properties may be ob tained by processing an integral multilayer photosensitive element d]imidazole:

in the presence: of naphth[1,2"

, naphth[ l,2 d]imidazole is effective to selectively shift,

i.e., slow, the speed of the blue silver halide emulsion of an integral multicolor dye developer photosensitive element, and that this selective speed shift may be effected as a function of the concentration of the naphth[l,2-d]imidazole. Assuming a multilayer negative in which the silver halide emulsion layer closest to the image-receiving layer is blue-sensitive and the sliver halideemulsion layer farthest from the image-receiving layer is red-sensitive, and the processing application containing naphth[ l,2-d]imidazole first permeates the blue-sensitive silver halide emulsion layer, the blue speed will be slowed down in a controlled manner, with little or no effect upon the green and red speeds. This effect is most desirable in eliminating a bluish cast present in flesh tones without adversely affecting the overall color balance, including the neutral reproduction. The mechanism by which this surprising effect is achieved is not known. It has been found that benzimidazole at an equimolar concentration does not give this selective effect, affecting both the blue and green speeds.

Naphth[l,2-d]imidazole has been found to be most effective when used inv combination with a 6- alkylamino purine of the formula:

I N mi} wherein R is an alkyl group, it being understood that alkyl is intended to include aralkyl, such as where the alkyl group is a simple alkyl group, better results are generally obtained when the alkyl group contains more than one or two carbons. As will be apparent from the above, the alkyl group may be substituted,

.e.g., by halogen, alkoxy, etc. The use of 6-alkylamino purines in dye developer processes is the subject of the copending application of Edwin H. Land, Stanley M.

- EXAMPLE A multicolor photosensitive element using, as the cyan, magenta and yellow dye developers This invention will be further illustrated by the fol- 5 lowing example intended to be illustrative only.

cyan:

magenta:

yellow:

was prepared by coating a gelatin-subcoated 4 mil opaque polyethylene terephthalate film base with the following layers:

1. a layer of cyan dye developer dispersed in gelatin and coated at a coverage of about 53 mgs./ft. of dye and about 96 mgsi/ft. of gelatin;

2. a red-sensitive gelatino silver iodochlorobromide emulsion coated at a coverage of about 95 mgslft. of silver and about 70 mgs./ft. of gelatin;

3. a layer of a 60-30-4-6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide coated at a coverage of about 264 mgs./ft. of the copolymer and about 8 mgs./ft. of polyacrylamide;

4. a layer of magenta dye developer dispersed in gelatin and coated at a coverage of about 62 mgsJft. of dye and about 67 mgs./ft. of gelatin;

5. a green-sensitive gelatino silver iodochlorobromide emulsion coated at a coverage of about 70 mgs./ft. of silver and about 63 mgs./ft. of gelatin;

6. a layer containing the copolymer referred to above in layer 3 and polyacrylamide coated at a coverage of about 95 mgs./ft. of copolymer and about 12 mgs./ft.

of polyacrylamide;

7. a layer of yellow dye developer dispersed in gelatin and coated at a coverage of about 100 mgs./ft. of dye and about 59 mgs./ft. of gelatin;

8. a blue-sensitive gelatino silver iodobromide emulsion layer including the auxiliary developer 4- methylphenyl hydroquinone coated at a coverage of about 125 mgs./ft. of silver, about 80 mgs./ft. of gelatin and about 37.5 mgs./ft. of auxiliary developer; and

9. a layer of gelatin coated at a coverage of about 40 mgs./ft. of gelatin.

A transparent 4 mil polyethylene terephthalate film base was coated, in succession, with the following layers to form an image-receiving component:

1. as a polymeric acid layer, the partially butyl ester of polyethylene/maleic anhydride copolymer at a coverage of about 2,500 mgs./ft.

2. a timing layer containing about a :1 ratio of a -30-46 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide at a coverage of about 500 mgs./ft. and

3. a polymeric image-receiving layer containing a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4- vinylpyridine, at a coverage of about 300 mgs./ft. The two components thus prepared were then taped together to provide an integral film unit, with a rupturable container retaining an aqueous alkaline processing solution fixedly mounted on the leading edge of each of the components, by pressure-sensitive tapes, so that, upon application of compressive pressure to the container to rupture the containers marginal seal, its contents would be distributed between the image-receiving layer and the gelatin overcoat layer of the photosensitive component. The aqueous alkaline processing composition comprised:

Potassium hydroxide 4.59 g.

N-benzyl-u-picolinium bromide (50% solution in water) 1.25 g.

N-phenethyl-a-picolinium bromide 0.72 g.

Sodium carboxymethyl cellulose (Hercules Type 7H4F providing a viscosity of 3,000 cps. at 1% in water at 25C.) 1.07 g.

Titanium dioxide 41.8 g.

6-metl1yl uracil 0.29 g.

Lithium nitrate 0.097 g.

Benzotriazole 0.56 g.

6-methyl-5-bromo4- azabenzimidazole 0.028 g Colloidal silica aqueous dispersion (30% SiO 1.82 g.

carboxymethyl-ethylene diamine 0.82 g.

Naphth[ l,2-d] imidazole 0.4 g.

Lithium hydroxide 0.2 g.

6-benzylamino-purine 0.39 g.

Polyethylene glycol (molecular weight 6,000) 0.54 g

Water to make 100g.

The photosensitive element 'was exposed through the transparent support and the layers thereon to a multicolor 'stepwedge which included a simulated flesh tone density scale, and a layer approximately 0.0028 inch thick of the processing composition was distributed by passing the film unit between a pair of pressureapplying rolls and into a lighted area. The resulting laminate was maintained intact to provide a multicolor integral negative-positive reflection print which exhibited good color quality and separation.

The characteristic curves of the red, green and blue densities of the simulated flesh tone column of the multicolorimage obtained in the above Example are reproduced in FIG. 1. As a control, the described process was repeated omitting the naphth[ l,2-d] imidazole, and the red, green and blue densities of the simulated flesh tone column of the resulting control multicolor image are reproduced in FIG. 2. It will be readily apparent from a visual inspection of the respective H and D curves that the blue H and D of FIG. 2 is much closer to the green H and D curves than is the blue H and D curve of FIG. 1. This results in a bluish cast to the flesh tones. One useful guide to a relationship between the red, green and blue H and D curves which will produce pleasing flesh tones is to measure the difference in density units (a) between the green and red and (b) between the green and blue densities at the exposure level which produces a red density of 0.3 in the simulated flesh tone column of the multicolor reflection print. It has been found that pleasing flesh tones are obtained if the ratio of the red-to-green deltato the blue-togreen delta approximates I. These deltas were determined for the curves reproduced in FIGS. 1 and 2 as follows:

When the procedure described in the above example was repeated substituting a molar equivalent of benzimidazole for the naphth[ 1,2-d]imidazole, both the green and blue H and D curves were affected and the red, green and blue density ratio did not give pleasing flesh tones.

In general, it has been found that incorporation of naphth[ l,2-d]imidazole in the processing composition in a concentration of about 0.1 to 0.7%, by weight, is effective to provide useful shifting of the blue H and D curve relative to the green and red for improved flesh tone reproduction. The particular concentration most useful with a given photosensitive element and processing composition, of course, may be readily determined by routine testing.

While the invention has been illustrated as applied to the formation of integral negative-positive multicolor reflection prints, it will be understood that the invention also may be employed in the preparation of other diffusion transfer dye developer images, including monochromatic, black and white, and multicolor transfer images which are separated from the photosensitive light-reflecting layer is not provided by a pigment in the processing composition but is provided, e.g., by a preformed layer of titanium dioxide, and the imagereceiving layer is carried by the same support as the photosensitive layers, as taught in U.S. Pat. Nos. 3,594,164 and 3,594,165, bothissued July 20, 1971 to Howard G. Rogers.

Development is advantageously effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed in U.S. Pat. No. 3,173,786 issuedMar. 16, 1965 to Milton Green and Howard G. Rogers. Quaternary ammonium compounds which form an active methylene compound in alkali are especially useful.

Development may be effected in the presence of a colorless auxiliary or accelerating developing agent, such as a 3-pyrazolidone or a hydroquinone, such as 4'-methylphenylhydroquinone, which may be initially positioned in a layer of the photosensitive element or in the processing composition, in accordance v with known techniques.

The image-receiving element may be prepared according to'the disclosure of U.S. Pat. No. 3,362,819 issued Jan. 9, 1968 to Edwin H. Land and U.S. Pat. No. 3,455,686 issued July 15, 1968 to Leonard C. Farney, Howard G. Rogers and Richard W. Young.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed'is:

l. A diffusion transfer color process comprising exposing a photosensitive element comprising a bluesensitive silver halide emulsion having a. yellow dye developer associated therewith, a green-sensitive silver halide emulsion having a magenta dye developer associated therewith, and a red-sensitivesilver halide emulsion having a cyan dye developer associated therewith, applying an aqueous alkaline processing composition to said exposed photosensitive element to effect development and to form an imagewise distribution of unoxidized dye developer in undeveloped areas of each of said silver halide emulsions as a function of said development, said process including the step of transferring by diffusion at least a portion of said imagewise distributions of unoxidized dye developer to an imagereceiving layer in superposed relationship therewith to thereby provide a multicolor diffusion transfer image, said aqueous alkaline processing composition containing naphth[l,2-d1imidazole and contacting said bluesensitive silver halide emulsion before contacting said green-sensitive and red-sensitive silver halide emulsions.

2. A diffusion transfer color process as defined in claim 1 wherein there is also present during development a 6-alkylamino purine of the formula:

j N\ K,

wherein R is an alkyl group.

3. A diffusion transfer color process as defined in claim 2 wherein said 6-alkylamino purine is 6- benzylamino purine.

4. A diffusion transfer color process as defined in claim 1 wherein said naphth[ l ,2-d]imidazole is present in said aqueous alkaline processing composition in a concentration of about 0.1 to about 0.7 percent by weight of said processing composition.

5. A diffusion transfer color process as defined in claim 1 wherein a layer containing titanium dioxide is positioned between said image-receiving layer and said silver halide emulsion whereby said transfer image may be viewed without separating said image-receiving layer from said silver halide emulsion.

6. A diffusion transfer color process as' defined in claim wherein said titanium dioxide is initially present in said processing composition.

7. A photographic product for use in forming a diffusion transfer image in color comprising a photosensitive element comprising a support carrying a bluesensitive silver halide emulsion having a yellow dye developer associated therewith, a green-sensitive silver halide emulsion having a magenta dye developer associated therewith, and a red-sensitive silver halide emulsion having a cyan dye developer associated therewith; a second, sheet-like element positioned in superposed or superposable relationship with said photosensitive element; an image-receiving layer positioned in one of said elements; a rupturable container releasably holding an aqueous alkaline processing composition adapted, when distributed between a pair of predetermined layers carried by said photosensitive element and said second element, to contact said blue-sensitive silver halide emulsion before contacting said greensensitive and red-sensitive silver halide emulsions and to develop said silver halide emulsions and provide a diffusion transfer image in color on said imagereceiving layer; said processing composition including napth[ l,2-d]imidazol'e.

8. A photographic product as defined in claim 7 wherein said second element includes said imagereceiving layer carried by a transparent support, and said processing composition includes titanium dioxide.

9. A photographic product as defined in claim 7 wherein said naphth[ l,2-d]imidazole is present in said processing composition in a concentration of about 0.1 to about 0.7 percent by weight of said processing composition.

10. A photographic product as defined in claim 7 wherein said processing composition also includes a 6- alkylamino purine of the formula wherein R is an alkyl group.

11. A photographic product as defined in claim 10 wherein said 6-alkylamino purine is 6-benzylamino purine. 

1. A DIFFUSUON TRANSFER COLOR PROCESS COMPRISING EXPOSING A PHOTOSENTATIVE ELEMENT COMPOSING A BLUE-SENSITIVE SILVER HALIDE EMULSION HAVING A YELLOW DYE DEVELOPER ASSOCIATED THEREWITH A GREEN-SENSITIVE HALIDE EMULSION HAVING A MAGENTA DYE DEVELOPER ASSOCIATED THEREWITH AND A RED-SENSITIVE SILVER HALIDE EMULSION HAVING A CYAN DYE DEVELOPER ASSOCIATED THEREWITH, APPLYING AN AQUKEOUS ALKALINE PROCESSING COMPOSITION TO SAID EXPOSED PHOTOSENTATIVE ELEMENT TO EFFECT DEVELOPEMENT AND TO FORM AN IMAGEWISE DISTRUBITION OF UNOXIDIZED DYE DEVELOPER IN UNDEVELOPED AREASOF EACH OF SAID SILVER HALIDE EMULSION AS A FUNCTION OF SAID DEVELOPEMENT SAID PROVESS INCLUDING THE STEP OF TRANSFERING BY DIFUSSION AT LEAST A PORTION
 2. A diffusion transfer color process as defined in claim 1 wherein there is also present during development a 6-alkylamino purine of the formula:
 3. A diffusion transfer color process as defined in claim 2 wherein said 6-alkylamino purine is 6-benzylamino purine.
 4. A diffusion transfer color process as defined in claim 1 wherein said naphth(1,2-d)imidazole is present in said aqueous alkaline processing composition in a concentration of about 0.1 to about 0.7 percent by weight of said processing composition.
 5. A diffusion transfer color process as defined in claim 1 wherein a layer containing titanium dioxide is positioned between said image-receiving layer and said silver halide emulsion whereby said transfer image may be viewed without separating said image-receiving layer from said silver halide emulsion.
 6. A diffusion transfer color process as defined in claim 5 wherein said titanium dioxide is initially present in said processing composition.
 7. A photographic product for use in forming a diffusion transfer image in color comprising a photosensitive element comprising a support carrying a blue-sensitive silver halide emulsion having a yellow dye developer associated therewith, a green-sensitive silver halide emulsion having a magenta dye developer associated therewith, and a red-sensitive silver halide emulsion having a cyan dye developer associated therewith; a second, sheet-like element positioned in superposed or superposable relationship with said photosensitive element; an image-receiving layer positioned in one of said elements; a rupturable container releasably holding an aqueous alkaline processing composition adapted, when distributed between a pair of predetermined layers carried by said photosensitive element and said second element, to contact said blue-sensitive silver halide emulsion before contacting said green-sensitive and red-sensitive silver halide emulsions and to develop said silver halide emulsions and provide a diffusion transfer image in color on said image-receiving layer; said processing composition including napth(1,2-d)imidazole.
 8. A photographic product as defined in claim 7 wherein said second element includes said image-receiving layer carried by a transparent support, and said processing composition includes titanium dioxide.
 9. A photographic product as defined in claim 7 wherein said naphth(1,2-d)imidazole is present in said processing composition in a concentration of about 0.1 to about 0.7 percent by weight of said processing composition.
 10. A photographic product as defined in claim 7 wherein said processing composition also includes a 6-alkylamino purine of the formula
 11. A photographic product as defined in claim 10 wherein said 6-alkylamino purine is 6-benzylamino purine. 